Solution concentration control system



June 5, 1945- s. G. NOBLE ET AL 2,377,363

SOLUTION CONCENTRATION CONTROL SYSTEM Filed July 28, 1941 ZZ Z5 .r anea,.lms, m

UNITED STATES PATENT amuse OFFICE sow'rron concnfi'raa'non 09mi sizsrrmu Sidney'GNoble, and William L.

- eggigeygrthliafirann. L

' i illgsg -my 2a, 1941, Serlallhlo. 401.438

(oust- 7s) certain predetermined limits by utilizing the unbalance developed across an alternating current bridge circuit, one leg of which is composed of the resistance ofiered by the solution to the passage of current between electrodes submerged in the solution.

Specifically this unbalance is used to trip a gaseous type, grid controlled vacuum tube which operates the control equipment.

The voltage applied to the control element of 7 the tube. is maintained at the required value by pressed as follows: The control is dependent upon the ionization point of the tube which is constant and not upon the deionization point which is variable.

The feature of the invention which is a corollary to this object is that the control is initiated by the tube but not maintained thereby.

Another object of the invention is to provide a system including a tube for control purposes which breaks down ata point independent of the supply voltage, and same may be utilized in an over-regulated arrangement or an under-regulated arrangement with equal facility, s hereinafter pointed out.

The feature of the invention which is a. corollary to this object is that since the regulated voltage increases when the supply voltage decreases and vice-verse, the unbalance voltage which causes breakdown of the control tube adds to the regulated voltage to produce over regulation when the bridge polarity and regulator are properly adjusted or the unbalance. voltage subtracts from such voltage to produceunder-regulation.

A feature of the invention is that the voltage regulating system can be adjusted to produce overall consistency of operation with varying supplyvoltage not merely a constant voltage at a given point. The voltage regulating system when adiusted as described hereinafter to produce a perfectly regulated voltage at a value equal to the breakdown voltage of the control tube, is

left that way. The operation of the device in service .is dependent upon the amount of unbalance in the bridge circuit and regulation is not involved.

A still further feature of the invention is the overflow type of solutionconcentrate formation and its supply to the cleaning solution such that a mixing occurs and the control is responsive to the mixture and not the concentrate solution supply.

. Briefly, the system operates as follows: When the cleaning solution concentration becomes suffi- I ciently weak, the current flow through same from W solution;

one electrode to the other, both being exposed to the solution, causes the control system to operate. This is of cyclic character in that for each energization of the system a predetermined amount of solution concentrate is supplied to the cleaning If after such supply cleaning solution is 'suflicient, no further ener gization of the control is eifected until the concentration again reaches the critical low limit incident to normal use of such cleaning solution.

If, 'however, after initial energization of, the control and solution concentrate supply, the cleaning solution concentration be not sufflclent, the system is reenergized, and automatically, for an additional supply of solution concentrate to the cleaning solution and this cycle is repeated as often as necessary to finally provide the cleaning solution with a desired maximum concentra-' tion after which no further concentrate supply is eifected until by normal use of the cleaning solution the cleaning solution concentration is reduced to that low limit for which the control system is adjustedto provide replenishment of con-' centrate and to the desired amount and by repetitious or cyclic operation, if necessary, as described the concentration in the v portion of the system and the solenoid valve controlling the concentrate supply.

Fig. 3 is a view similar to Fig. 2 and of a portion of the circuit shown therein and modified by the inclusion of a step-up transformer.

Having briefly described the basic operation of the system, reference will first be had to Fig. l. Therein l indicates a container or vessel of the desired capacity and if desired, provided with hot and/or cold water supplies and a drain of controlled character. None of which is illustrated because obvious and conventional. This vessel contains the cleaning solution H.

At a higher elevation is another container or vessel l2. A conduit I 3 from the bottom I thereof leads to vessel and discharges therein by gravity at l5 substantially opposite the electrode unit I6 having solution exposed electrodes H and 18 to which reference will be had later.

The numeral 19 indicates a pressure fresh water supply. Usually this is at city pressure of about 40 lbs. The numeral 20 indicates a metering valve in said line. The numeral 2| indicates an electrical operable valve structure which is normally constrained to closed position but which when electrically energized is held full open in opposition to its constraint for so long a period as energy is applied thereto. As previously stated, this is a predetermined interval in the control cycle.

The end 22 of said dual valve controlled fresh water supply line I9 terminates above the liquid level 23 in container l2. However, end 22 does not discharge directly into the container but into chamber 24 therein open at its up er end 25 and terminating above level 23.

The lower end 25a terminates above the bottom 14; hence, fresh water supplied to chamber 24 flows into the vessel I! near the bottom and percolates upwardly through the powdered chemical material 26.

The vessel l2 contains another chamber 21, the upper end 28 of which determines the level 23. Conduit i3 communicates with the lower end of chamber 21 and is the sole communication with vessel l2. There may be applied to end 28 suitable guards, screens et cetera, to prevent overflow of powdered chemical to chamber 21.

When valve 2| is opened, a regulated continuous supply of fresh water enters chamber 24 and in passing upwardly through chemical 28 becomes saturated therewith. The saturated or nearly saturated solution (solution concentrate) thus continuously overflows, by fresh water displacement, into chamber 21 from which it flows by gravity to vessel l0.

' This constitutes the liquid portion of the system. As stated such overflow supply is repeated as often as necessary or required. Note that the concentrate enters vessel Ill opposite terminals or electrodes ll-i8 and hence, concentrate dispersion in the cleaning solution unit occurs before the electrical system is responsive to concentrate addition.

Reference will now be had to Fig. 2, wherein the preferred embodiment of the electrical portion of the system is illustrated diagrammatically.

Before proceeding to a detail description of the control system, proper, it is to be observed that there is provided a motor 30 which through a reduction drive slowly rotates shaft 3! on which is mounted two cams 32 and II. Cam 33 is associated with a switch 34-35 controlling current supply to the electrically operable valve 2 l When the motor stops rotating, the cam 33 is positioned as illustrated and switch "-8! is open and the valve is not energized. This may be a solenoid valve and is preferably connected directly across the supply mains so that it does not affect the constants of control circuit. The high point "a of the cam 38 moves open circuit constrained switch member 34 to contact member I! and as long as the high point is effective, the valve is energized and hence, open to supply fresh water as previously described.

The other cam 32 has a relieved portion "a. when the motor is first energized, as hereinafter described, the cam 3! moves the relieved portion from adjacent the motor circuit maintaining switch and the cam then closes that switch to maintain motor operation until the motor circuit maintaining switch again registers with relieved portion 32a of cam 32. The motor circuit is then broken. The timing is such that the valve is deenergized at this time. The interval of open valve operation is determined by the arcuste length of portion 33a and the rate of rotation of shaft 3 l This is about one revolution per minute. The concentrate solution supply, as illustrated by portion 33a, is about thirty seconds. It may be greater or less as determined by the length of said .cam portion 330. A satisfactory motor is a synchronous motor'operating at about 3600 R. P. M. and the reduction gear ratio is about 3600zl relative to the cam shaft ii.

In Fig. 2 the numeral 40 indicates one supply main and ll another of a 1l0-volt conventional alternating current source. A transformer primary 42 is directly connected thereto at 44 and 43, respectively. This is the source of power for the control. Line I! from Junction 43 connects to one terminal of a green signal 41, one terminal of a red signal ll, one terminal of the motor ll and one terminal of the electrically operable valve 2i.

Line 46 from Junction 44 connects to Junction ll from which extends line 49 to valve switch member 34. Valve switch member I! is connected by line ll to the other terminal of the electrically operable valve Ii. A line 52 from Junction 5| connects' to switch member 53 normally constrained to contact with switch member 54 so long as switch member I; has its cam actuable portion seated in relieved portion 32a of cam 32.

Switch member 54 is connected by line II to contact 50 of a relay or solenoid operable switch. The other contact 51 thereof herein normally contacts contact 58 and connects by line 5' to the other terminal of the green light. Hence, when the motor is not energized and the relay or solenoid I! controlling said switch is not energized, the green signal light is energized.

Another switch normally in open circuit relation includes contacts II and I. It is closed when the solenoid or relay 5! is energized. Contact ii is connected by line 62 to line 88 connecting to the other terminals of the red signal light ll and the motor II. Hence, the motor and red signal light are in multiple.

Contact of the second relay switch connects by line N to Junction ll. When the relay ll is energized the green signal light is deenergized because switch "-51 is open, and the motor and red signal light are energized because switch BHI is closed, this circuit being junction l4, line 48, Junction Ml, line N, switch HI, line 82, the line I, the red light and motor, line 4! and junction ll.

Upon relay energization, therefore, motor ll rotates cam 32 and II counterclockwise to open will be energized and the motor will rotate cam 82 until notch 82a again registers with switch member 88 whereupon the motor maintaining circuit will be opened.

At this point attention. is called to another normally closed switch 88-88, contact 88 being connected to line 10 and contact 88 being connected to line H. When switch 58 is associated with notch 82a of cam 82 switch84-88 (green light circuit) is closed as well as switch 88-88.

When switch member 83 does not register with notch 82a, switches 5358 and 68-48 are open and switch 83-88 is closed. Hence, when the motor maintaining circuit is closed the circuit through lines I0 and II is open at the switch 88-68. Herein members 58 and '68 are electrically insulated from each other but mechanically connected for simultaneous movement.

Reference will now be had to the central and lower portions of Fig. 2. In the lower right portion is illustrated a Wheatstone bridge having two fixed legs 12 and I8. The line II connects to the junction of these two legs.

A secondary ll of the transformer is connected by lines l1 and I8 to the other ends 15 and I8 of the legs 13 and 72, respectively. A third leg 18, has an adjustment 80 and is connected by line 8| to the starting anode of tube 82. Line 88 at one end connects to said line 8| at the adjustment 80 and at the opposite end to terminal ll of the plug it before mentioned. The other terminal I8 is connected by line 84 to junction I8 of the bridge. Hence, the lines 88-88 and terminals I|-l8 and the cleaning solution between said terminals constituents the other or fourth leg of the bridge.

Tube 82 has the anode 85 and cathode 88, This tube is normally cold and when energized or ionization occurs therein, current flows to the relay 58 because line 81 therefrom through resistance 88 is connected to the anode 85. Line 88 is connected to the cathode 86 at one end and tap 80 on secondary 8| of the transformer. Line 82 is connected to tap 88 on said secondary as well as the other terminal of relay 58. Hence, when the tube is conditioned, the relay is enerline 10 before mentioned, including cam operable switch member 88. A resistance I08 is connected at I08 to line H. and at 0 to line 88.

The foregoing constitutes the several circuit elements and connections.

The voltage applied to the control element of the tube 82 is maintained at the requiredvalue by means of an adjustable voltage taken from a regulated source of voltage and applied to the controlling element of the tube in series with the unbalance voltage of the bridge circuit.

In a voltage regulating system, proper, or normal regulation is accomplished when the output voltage is constant regardless of whether the input voltage rises above or drops below normal input voltage. Over-regulation occurs when the output voltage decreases as the result of an in-.

crease in the input voltage or vice-verse. Underregulation occurs when the output voltage increases as the result of an increase in the input voltage or vice versa, that is, under-regulation does not completely eliminate the normal change in the output of the regulating device while overregulation more than compensates for such a change.

In the present device, two voltages are added- (1) a regulated voltage which is obtained from the voltage divider (resistance I05) between points I06 and I01, and (2) an unregulated voltage which is the unbalanced voltage taken from the bridge circuit between the junction of resistances l2 and I3 and the junction of lines 8| and 83. In order that the sum of these two volt ages shall be constant with either a rising or a dropping supply voltage, it is necessary that the regulated portion of the voltage be properly adjusted to compensate for the change occurring in the unregulated portion of the voltage. This can be accomplished in two ways: 1) if the polarity of the two voltages is such that the unregulated voltage adds to the regulated voltage, the regulating system must be so adjusted (by means of the variable resistance 88) that the the regulated voltage drops slightly when the supply voltage rises and vice-versa; (2) if the gized which as before stated initially closes the I motor pick-up circuit or starting circuit. A condenser 84 may bridge the relayasshown bein connected across lines 81 and-82.

The secondary 80 of the transformer has end tap 85, Opposite end tap 88 and another intermediate tap 81. A resistance 88 bridges taps 80-41 and a manually adjustable contact 88 determines the adjustment at said resistance. Contact 98 connects by line' I00 to a 'voltage regulator tube IOI. Tap 95 is connected to a resistance I02 and by line I 08 to the other terminal of tube I0'I.

A line I04 connects oneend of resistance I05 to line I03 at tube IN. The other end of said resistance is connected at I 08 to line 89 before mentioned. A manually adjustable contact I0! is associated with resistance I05 and connected to polarity of the two voltages is such that the unregulated voltage opposes (or subtracts from) the regulated voltage the regulating system must be so adjusted that the regulated voltage is underregulated.

If it is considered that the algebraic sum of the two voltages mentioned above is the output of a regulating device, both of the conditions mentioned above produce perfect regulation, that is both produce a total output voltage which is independent of the line voltage.

It might be well to keep in mind that the term 'voltage" is not an exact term, as there are several kinds of voltage: namely, effective voltage, average voltage, peak voltage, et cetera. voltage with which the present invention is concerned is that which causes the tube to ionize and thisv is practically the peak value of the voltage. It is this fact which makes possible the use of so simple a form of voltage control device as this method of voltage control produces a badly v distorted wave form.

conjunction with the contactsof relay 58 con- The.

nected into the anode circuit or the controlling tube 82. The circuit is so devised and the cams so constructed as to provide a three-step process consisting of a test period, a replenishing period, and a mixing period, the replenishing and mixing periods occurring only when the results of the test indicate a deficiency in the concentration of the solution in vessel Hi. The test period may be of long or short duration. It will be long it concentration reduction is slight. It will be short if such reduction is rapid. It may be infinitesimal if after one cycle, the cleaning solution is still too low in concentration.

The control voltage is supplied to the tube I2 through contacts (SS-69 in the cam controlled circuit, including lines 101I, which operating in conjunction with a grounding resistor I08 permits extinguishing the tube 82 as soon as the cam 32 has moved far enough to cause the motor driving the cam to be locked in through contacts 5365 operated by the cam. This type of operation results in the control being dependent only upon the breakdown or ionization point of the tube 82 (which is stable for a cold tube) and is The circuit operating the lights is so arranged that the only time the green light can be on and the red light ofi is when the cam is in the "normal position and the main control relay 59 is not energized. This combination occurs only when the control circuit is in the test condition and the resistance offered by the electrodes ll-l8 and associated solution is of such value as to indicate a satisfactory concentration in the solution in vessel ii.

The electrolytic condenser 94 of rather high capacity (10 mi. to 100 mf., depending upon the constants of the relay) and the relay 59 is a D. C. relay operating on A. C. and it prevents relay chatter, thereby eliminating noise and it provides a time delay of a fraction of a second so that if the ionization tube flashes or has a tendency to flash, the control circuit is not operated unless and until the concentration condition positively requires operation that causes the tube to ionize and remain ionized for a suilicient interval to insure setting up the control for motor and valve operation, et cetera.

It has been established that when the lin voltage varies from a normal voltage of 115 volts by as much as 10 volts, either above or below normal, the voltage applied to the control element of the tube does not vary more than a few hundredths of a volt. The tube 82 illustrated can be of RCA-AM type. Tube l0! can be of VR-105-30 type or VR-150-30 type. The first mentioned tube in each instance is preferred in the specific circuit diagram illustrated.

The line H may include points I20 which is a jumper connection in the base of the regulator tube IOI. Removal of tube IOI thus opens the primary circuits and revents the application of excessive voltages to the secondary circuits. This is a protective factor.

Whenever desired, a small step-up transformer A may be inserted in the output or the bridge While the invention has been illustrated and described in great detail in the drawing and loregoing description, the same is to be considered as illustrative and not restrictive in character.

The several modifications described herein as well as others which will readily suggest themselves to persons skilled in this art, all are considered to be within the broad scope or the invention, reference being had to the appended claims.

The invention claimed is:

1. In a concentration control system comprising a solution container, 9. pair of electrodes exposed to the solution therein, the latter with the electrodes comprising part of a control circuit, and a second container including a, concentrated make-up solution, the combination of a liquid supply to the second container and discharging thereto near the bottom thereof, an overflow discharge from the second container to the first container, said second container between the bottom discharge thereto and overflow discharge therefrom containing soluble chemical for concentrated solution formation, electrically actuated valve means for controlling the liquid supply from the second container to the first container, the liquid supplied to the second container percolating upwardly through the chemical, and a control circuit for electrically actuating said valve means, said circuit including the aforesaid electrodes and being so arranged as to respond to the first mentioned container solution concentration falling below a predetermined minimum value to begin cycles of valve operation comprising the opening, holding open for a predetermined interval of time and closing of the valve means, the cycles of valve operation continuing until the concentration in said first mentioned container exceeds the predetermined minimum value.

2. A system as defined by claim 1 wherein a pick-up circuit is included in the control circuit and is actuated by electric energy across the electrodes, same being directly responsive to electrode exposed solution concentration, a predetermined minimum solution concentration to which the electrodes are exposed actuating the pick-up circuit, a power circuit for the valve means, and a maintaining circuit responsive to pick-up circuit control and having a predetermined maintaining interval for maintaining the valve means power circuit for the maintaining interval, the valve means power circuit being responsive to both pickup and maintaining circuits for initial closing and subsequent maintaining of said valve means power circuit.

3. 'A system as defined by claim 1 wherein a pick-up circuit is included in the control circuit and is actuated by electric energy across theelectrodes, same being directly responsive to electrode exposed solution concentration, a predetermined minimum solution concentration to which the electrodes are exposed actuating the pick-up circult, a power circuit for the valve means, and a maintaining circuit responsive to pick-up circuit control and having a predetermined maintaining interval for maintaining the valve means power,

circuit for the maintaining interval, the valve means power circuit being responsive to both pick-up and maintaining circuits for initial closing and subsequent maintaining or said valve means power circuit, and having a predetermined period of operation less than the maintaining circuit period, the difference between periods constituting a dispersing period for concentration discharge dispersion in the container.

4. In a concentration control system comprising a solution container, a pair of electrodes exposed to the solution therein, the latter with electrodes constituting part 01' a control circuit. a second container including a concentrated make-up solution and arranged for discharge to the first mentioned container, and electrically operable valve means controlling the discharge of concentrate solution to the first mentioned container, the combination of a pick-up circuit in the control circuit, actuated by electric energy across the electrodes, the pick-up circuit being directly responsive to and actuated by a minimum value of electrode exposed solution concentration, a power circuit for the valve means, and a main taining circuit responsive to pick-up circuit control and having a predetermined maintaining interval for maintaining the valve means power circuit for the maintaining interval, the valve means power circuit being responsive to both pick-up and maintaining circuits for initial closing and subsequent maintaining of said valve means power circuit closed when the solution concentration in said first mentioned container falls below the predetermined value to effect cycles of operation of the valve means which comprises opening, holding open for a. predetermined interval oi. time and closing said valve means. the cycles of operation continuing until the concentration in said first mentioned container exceeds the predetermined minimum value.

5. A concentration control system as defined by claim 4 wherein the power circuit has a predetermined period of operation less than the maintaining circuit period. the diilerence between periods constituting a dispersing period for the make-up supply to the container to disperse therein.

8. A system as defined by claim 1 wherein a pick-up circuit is included in the control circuit and is actuated by electric energy across the electrodes, same being directly responsive to electrode exposed solution concentration, a predetermined minimum solution concentration to which the electrodes are exposed actuating. the pick-up circuit, a power circuit for the valve means, and a maintaining circuit responsive to pick-up circuit control and having a predetermined maintaining interval for maintaining the valve means power circuit for the maintaining interval, the valve means power circuit being responsive to both pick-up and maintaining circuits for initial closing and subsequent maintaining or said valve means power circuit, and having a predetermined period of operation less than the maintaining circuit period, the difference between periods constituting a dispersing period, the control circuit including signal means for selectively indicating sufllcient and insumcient concentrations in said first container.

7. A concentration control system as defined by claim 4 wherein the power circuit has a predetermined period or operation less than the maintaining circuit period, the diflerence between periods constituting a dispersing period, the control circuit including signal means for selectively indicating sufilcient and insuillcient concentrations in said first container.

8. In a concentration control system, the combination of a Wheatstone bridge arrangement, one leg of which includes a pair of electrodes exposable to a solution, variation in the concentration thereof varying current fiow through the electrode leg, a control tube connected to said bridge arrangement and responsive to electrode leg current variation, a concentrate liquid supply,

' a valve controlling such liquid supply to the solution, means controlling said valve, and electrically operable means responsive to tube operation for predetermined operation of the valve controlling means, the tube being of ionizable character, the electrically operable means including a pick-up circuit receiving electrical energy from said tube, and a maintaining circuit for supplyin electrical energy to the electrically operable means, the pick-up circuit being responsive to tube operation for closing the maintaining circuit, the latter having a predetermined interval of operation, the control tube being ionizable when the solution concentration drops to a predetermined minimum, the valve holding open for the predetermined interval, the cycle of valve opening and closing continuing until the solution concentration exceeds the predetermined minimum value.

9. A system as defined by claim 8 wherein said circuits are arranged to discontinue tube operation by automatically opening the pick-up circuit after the maintaining circuit has been established, the latter having a predetermined maintaining interval for energizing the electrically operable means for a predetermined interval only.

10. A system as defined by claim 8 wherein said circuits are arranged to discontinue tube operation by automatically opening the pickup circuit after the maintaining circuit has been established, the latter having a predetermined maintaining interval for energizing the electrically operable means for a predetermined interval only, and means automatically operable at the end 01' the maintaining interval for not only opening the maintaining circuit but simultaneously reconditioning the pick-up circuit for tube operation and control.

SIDNEY G. NOBLE. WILLIAM L. WOLGEMUTH. 

